Moderna and Pfizer-BioNTech vaccines prioritize T cells to fight SARS-CoV-2 variants

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T cells from people who have recovered from COVID-19 or have received Moderna or Pfizer-BioNTech vaccines can still recognize several SARS-CoV-2-related variants. Credit: La Jolla Institute for Immunology

Researchers at the La Jolla Institute of Immunology (LJI) have found that T cells from people who have recovered from COVID-19 or received Moderna or Pfizer-BioNTech vaccines are still able to recognize several variants. related to SARS-CoV-2.

His new study, published online July 1, 2021 a Cell Reports Medicine, shows that both the CD4 + “helper” T and CD8 + “killer” T cells can still recognize mutated forms of the virus. This reactivity is key to the body’s complex immune response to the virus, which allows the body to kill infected cells and stop serious infections.

“This study suggests that the impact of the mutations found on the variants of concern is limited,” says LJI professor Alessandro Sette, Dr.Bio.Sci., Lead author of the study and a member of the LJI Infectious Diseases and Vaccines. “We can assume that T cells would still be available as a line of defense against viral infection.”

The researchers point out that the study only deals with how the body’s T cells respond to variants of concern (VOCs). The researchers point out that several of these variants are related to lower levels of antibodies against the virus.

The current study includes data on four of the most prevalent VOCs. Ongoing studies have been extended to a larger group of variants, including the Delta variant (B.1.617.2), which became prevalent after this study was initiated. The team has also established relationships with more than 20 different laboratories around the world to help monitor T cell reactivity to VOCs.

“These variants remain a concern, but our study shows that even if there is a decrease in antibodies, as other studies have shown, T cells remain largely unaffected,” says Dr. Alba Grifoni , doctor. “Vaccines continue to work.”

The Johnson & Johnson / Janssen COVID-19 vaccine was not part of this study because it was not available at the time of study launch.

LJI results guide COVID-19 vaccine efforts

This study was previously published online as a prepress in March 2021. The findings were highlighted by the director of the National Institutes of Allergy and Infectious Diseases Anthony Fauci, MD, at a White House press conference on 31 of March.

“We increasingly know that these CD4 + and CD8 + T cells are very important because they cross-react against certain viral variants,” Fauci said.

In the time since the paper was first published, researchers have nearly tripled their cohort of patients and performed an additional method of rigorous statistical analysis. “We’ve also added a cohort of unexposed donors,” says the study’s first author, Alison Tarke, a doctor. student at the University of Genoa, guest at LJI’s Sette Lab.

For the new study, researchers analyzed T cells from three different groups: people who had recovered from COVID-19, people who had received Moderna or Pfizer-BioNTech vaccines, and people who had never been exposed to SARS. -CoV-2 (from samples taken before the pandemic).

Both recovered and vaccinated subjects were likely to have T cells that recognized the “ancestral lineage” of SARS-CoV-2. This was the original strain that emerged at the beginning of the pandemic; however, the virus has mutated since December 2019 and several variants have been identified as VOCs.

The question was whether people with T cells trained to recognize the ancestral strain would also recognize the new variants. The researchers tested the T cell responses of the donor groups against four prominent VOCs: Alpha (B.1.1.7), Beta (B.1.351), Gamma (P.1), and Epsilon (B.1.427 / B.1.429).

The researchers found that both vaccinated individuals and recovered patients had reactive T cells that could target these variants. This is good news for anyone who has received one of the two mRNA vaccines and for anyone who has recovered from any variant of the virus.

“With this study, the underlying message is optimistic,” Tarke adds. “At least in terms of the response of T cells, your immune system is still able to recognize these new variants and your T cells will be able to respond.”

Similar results reporting largely unaffected T cell reactivity have been presented through independent studies published in Nature i Scientific immunology.

LJI study co-author and professor Shane Crotty, Ph.D., says this research highlights the importance of recruiting T cells in the fight against SARS-CoV-2.

“COVID vaccines do a fantastic job in making antibodies that stop SARS-CoV-2 infections, but some of the vaccines do it less well when it comes to stopping variant infections,” Crotty says. “You can think of T cells as a backup system: if the virus outgrows antibodies, if you have vaccinated T cells, T cells can still stop the variant of coronavirus infection before they contract pneumonia “.

Researchers are now looking for ways to take advantage of the flexibility of the T cell response. With T cells already working hard to recognize SARS-CoV-2 variants, Grifoni says future shots of “reinforcement “could increase immunity by encouraging the body to produce more antibodies against variants and / or by adding additional parts of the virus recognized by T cells.

“T-cell epitopes are very well preserved among SARS-CoV-2 variants, so incorporating T-cell targets into future COVID vaccines could be a smart way to ensure that future variants they can’t escape the vaccines, ”Crotty adds.

There is also the possibility that current SARS-CoV-2 research may one day lead to a universal vaccine, “pan-coronavirus”. This type of vaccine will enable the body to recognize the structural details, such as elements of the ear protein, that all coronaviruses have in common.

“This research shows that it is a pan-coronavirus it’s doable, ”Grifoni says.

The group is now studying a much larger group of 12 different variants of concern (VOC) and variants of interest (VOIs), including the Delta variant (B.1.617.2), Eta (B.1.525), Iota (B .1.526), ​​Kappa (B.1.617.1), Lambda (C37) and variants B.1.526.1, B.1.617.3, R1 and B.1.1.519.

Sette says he would also like to study the T cells of people who have been infected with the variants and see how these T cells react to the ancestral strain of the virus.


Structural changes in the alpha and beta variants of SARS-CoV-2 were identified


More information:
Cell Reports Medicine (2021). DOI: 10.1016 / j.xcrm.2021.100355 , www.cell.com/cell-reports-medi … 2666-3791 (21) 00204-4

Citation: Modern and Pfizer-BioNTech Major T-Cell Vaccines to Combat SARS-CoV-2 Variants (2021, July 1) Retrieved July 1, 2021 at https://medicalxpress.com/news/2021 -07-modern-pfizer-biontech-vaccines-first-cells.html

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